Omega-tricosenoic acid (22-tricosenoic acid) has been of interest for ultra thin layer photoresists (see Barraud, A. et al., J. Colloid Interface Sci., 1977, 62, 509; Barraud, A. et al., Thin Solid Films, 1980, 68, 91; Barraud et al., Solid State Tech., 1979, August, 120; Fariss, G. et al., Thin Solid Films, 1983, 99, 305; and Peterson, I. R. et al., Thin Solid Films, 1983, 109, 371. The synthesis routes in the literature for this compound involve many steps (see Barraud, A. et al., J. Colloid Interface Sci., 1977, 62, 509; Stenhagen, E., Arkiv Kemi, Min. O. Geol., 1949, 1, (13), 99; and Bowman, R. et al., J. Chem. Soc., 1952, 3945. The products are not adequately pure for photoresists because of the small amounts of double bond migration and hydrogenation that occur in the final synthesis step, i.e., the Wolff-Kischner reduction (or the Huang-Minlon Modification) of the intermediate omega-unsaturated keto acids. These side reactions have been noted before (see Sisido, K. et al., J. Org. Chem. 1962, 27, 3722). Even when milder reduction conditions (Hunig, S. et al., Ber. 1962, 95, 2498) or the sodium borohydride reduction of the tosyl hydrazone of the keto group (Gunstone et al., Chem. Phys. Lipids, 1967, 1, 209) are used, small amounts of these side reactions occur.
The presence of trace amounts of by-products with internal double bonds, no double bonds or shorter or longer chain lengths interfere with the x-ray or electron beam polymerization of the terminal double bond. Thus, high purity is necessary for high resolution in the resist by electron beam microlithography (Barraud et al., Solid State Tech., 1979, August, 120).